Atrial fibrillation (AF), the most common cardiac arrhythmia, is associated with an increased risk of stroke and systemic embolism.
Oral anticoagulation with vitamin K antagonists (VKAs), such as warfarin, has historically been the mainstay of long-term
thromboprophylaxis in AF patients. However, although highly effective, VKAs have a number of limitations that make their use difficult
and cumbersome in clinical practice. They have a slow onset and offset of action, narrow therapeutic window, marked dose-response
variability, and multiple food and drug interactions, and require frequent coagulation monitoring and dose adjustments. To overcome
VKA drawbacks, several new oral anticoagulants have been recently developed for use in AF, and three of them, the direct thrombin inhibitor
dabigatran etexilate and the direct factor Xa inhibitors rivaroxaban and apixaban, have completed phase III trials. New agents
have proven to be noninferior or superior to warfarin for AF-related stroke prevention, with similar or better safety profiles. These new
drugs, with their predictable anticoagulant effect that allows for fixed dosing with no need for coagulation monitoring, have the potential
to greatly simplify anticoagulation therapy for AF. Dabigatran etexilate and rivaroxaban are already approved in the United States and
Europe for stroke prevention in nonvalvular AF, and dabigatran etexilate has entered current AF guidelines as an alternative to warfarin.
However, some issues with new compounds are still unresolved, such as the lack of antidotes and standardized tests to measure drug activity.
Active postmarketing monitoring surveillance of effectiveness and safety is required in the implementation of new anticoagulant
Keywords: Atrial fibrillation, anticoagulant therapy, apixaban, dabigatran, rivaroxaban, stroke prevention, thromboembolism, new oral anticoagulants,
cardioembolic stroke, factor Xa, thrombin, factor Xa inhibitors, thrombin inhibitors, warfarin.
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